Saturday, August 27, 2005

The Russian VIC Cipher

The nickel message
Probably the most notorious pencil-and-paper cipher was the VIC cipher, named after Soviet spy Reino Hayhanen, codename Victor. In 1953, the FBI discovered a code message on a microfilm in a hollow nickel.

All attempts to break the message failed. Hayhanen eventually revealed the method to decipher the message when he defected in 1957. This cipher shows how strong encryption can be, without any crypto device or computer program.

The cipher used a date, a random number, and a 20 letter keyphrase to encrypt the message. The keyphrase was divided into two groups and transformed into a serie of numbers. Combined with the date and random number, they were used to generate 50 random digits by chain addition. The ten last digits were then used as header for a straddling checkerboard. The text is converted from letters into digits with this checkerboard.

A transposition, also based on the keyphrase, date and number, was used to generate a series of digits. Some of the generated digits served as a sequence header for a first simple transposition of the text (which was already encrypted with the checkerboard) and another part of the generated digits served as a header for a more complex disrupted transposition.

Despite being a pencil-and-paper cipher, it proved to be a highly secure cipher and the strongest ever, known to be issued for use in the field. Only Hayhanen's information enabled the FBI to reveal the content of the secret message.

More on the Hayhanen story can be found on the FBI site. A detailed description of the original message and the VIC cipher, titled Number One From Moscow and written by David Kahn, is found in the CIA library. Another example is found at John Savard's site. A software version of the SECOM cipher, which also uses a straddling checkerboard and double disrupted transposition, similar to the VIC cipher, is available as freeware on my Dropbox.


Anonymous said...

Thanks for pointing to most famous event in Cold war. Its interesting to look to the another description of VIC cipher and spy case of Rudolph Abel from CIA and David Kahn point of view. It can be found at NUMBER ONE FROM MOSCOW.

Matt Crypto said...

VIC is pretty cool. It's complex, but the advantage is that you can hold all the details and keys in your head. You don't need to keep any incriminating documents.

I also like the key deriviation procedure, which protects the key even if the main system is known and the attacker can get cribs for individual messages.

BTW Dirk, are SECOM and PPC-xx historical ciphers, or are they your own inventions?

GRip said...

Number One from Moscow als PDF Datei ->